2921.22 - Hexamethylenediamine and its salts:

This HTS category, 2921.22, specifically covers hexamethylenediamine and its salts. Hexamethylenediamine (HMDA) is an organic compound with the chemical formula H₂N(CH₂)₆NH₂. It is a diamine, meaning it contains two amine functional groups, and its acyclic structure places it within the broader classification of acyclic polyamines. Its primary use is as a precursor in the production of nylon 6,6. Its salts, formed by reaction with an acid, are also included in this classification.

This category is distinguished from its sibling, 2921.21.00.00, which is reserved for ethylenediamine and its salts. While both are acyclic diamines, hexamethylenediamine has a longer carbon chain (six carbons) compared to ethylenediamine (two carbons), leading to distinct chemical properties and end-use applications. The other sibling, 2921.29.00, serves as a residual category for all other acyclic polyamines and their salts not specifically enumerated.

Under 2921.22, two subcategories exist. The primary subdivision is 2921.22.05.00, which specifically identifies hexamethylenediamine adipate, also known as Nylon salt. This salt is an intermediate in the production of nylon 6,6. The remaining "Other" subcategory serves to capture any other salts of hexamethylenediamine not otherwise specified.